Oil seal for rotary mechanism

ABSTRACT

The dual-sealing oil seal for a rotor of a rotary mechanism which has a plurality of circumferentially spaced webs extending substantially radially between the spaced concentric legs of the oil seal to accelerate oil between the legs to the angular speed of the rotor.

United States Patent 1191 UNITED STATES PATENTS Paschke 4l8/l42.

Eierman June 11, 1974 OIL SEAL FOR ROTARY MECHANISM 3,171,590 3/1965 Bentele et al 3,265,045 8/1966 Bensinger et al. [75] Dmkwa" Emma, Lmdam 3,400,939 9/1968 Jones 418/142 Germany [73] Assignees: Audi Nsu Auto Union FORElGN PATENTS OR APPLICATIONS Aktiengesellschaft, Neckarsulm; 1,180,504 2/1970 Great Britain 4l8/l42 Wankel G.m.b.H., Lindau Bodensee. both'of Germany Primary ExammerCarlton R. Croyle [22] Filed: Jan. 5, 1973 Assistant Examiner-J0hn J. Vrablik pp No.1 321,235 Attorney, Agent, or Fzrm-Arthur Frederick [30] Foreign Application Priority Data 4 [57] ABSTRACT Jan/21, 1972' Germany 2202899 The dual-sealing oil seal for a rotor of a rotary mecha- [52] US. Cl. 418/142 nism which has a plurality of circumferentially spaced [51] Int. CL... F0lc 19/00, F04c 15/00, F040 27/00 webs extending substantially radially between the [58] Field of Search 418/91, 142; 277/81 R spaced concentric legs of the oil seal to accelerate oil between the legs to the angular speed of the rotor. [56] References Cited 8 Claims, 5 Drawing Figures BACKGROUND or THE INVENTION As exemplified in the U.S. Patents to Paschke et al, U.S. Pat. No. 3,l79,33l;'Bentele et al, U.S. Pat.- No. 3,171,590; Jones et al U.S. Pat. No. 3,180,563; Tado, U.S. Pat. No. 3,396,708 and Jones, U.S. Pat. No. 3,400,939,0il seals are disposed in each of theend faces of the rotor of rotary mechanisms of the Wankel type so as to seal the interstices between the rotor end faces and the adjacent end walls of the housing. The oil seals function to prevent lubricating oil, which is delivered to the shaft eccentric area for lubricating the shaft bearings and/or passed to the interior of the rotor for effecting cooling of the latter, from flowing radially outwardly and into the working chambers of the rotary mechanism and contaminating the fluid therein and resulting in excessive oil consumption.

As disclosed in the US. Patent to Bentele et al, U.S. Pat. No. 3,171,590, the problem of maintaining an oil seal under the distortions of the'seals due to the varying centrifugal forces and varying operating temperatures (when used as a combustion engine) to which the rotor and housing are subjected, was at least partially solved SUMMARY OF THE INVENTION Accordingly, the present invention contemplates an improveddual-sealing oil seal of the type disclosed in U.S. PBL'NO. 3,171,590 for a'rotary mechanism of the Wankel type, which oil seal is provided, in the space defined between the two concentrically spaced sealing edges or legs and a ring shaped body portion, with a plurality of circumferentially spaced webs or ribs which radially-extend between the sealing edges. This oil seal construction prevents distortion of the oil seal under the pressure exerted by the oil entrapped in the space between the sealing legs in the area diametrically opposite the cresent-shaped vent opening, and the resultant lifting or disengagement of the oil seal, since the oil entering each of the plurality of chambers or spaces defined by the sealing edges and the ribs is entrapped and is thereby angularly accelerated to the speed of the rotor so as to be carried to where the resultant acceleration force causes the oil to flow out of each of the chambers as they come into registry with the crescent shaped vent opening. This obviates the oil pressure build up problem in conventional dual-sealing oil seals having an annular chamber where the oil in the annular chamber, under the centrifugal forces (acceleration forces) is not propelled to 'the crescent-shaped vent opening for discharge from the annular chamber.

To prevent gas, which may leak past the gas seals car-' ried in each of the rotor end faces and enter the chambers between the sealing edges, from building up to lift the oil seal in the area diametrically opposite the crescent-shaped vent opening, gas vent passages are provided in the outer sealing edge. Each gas vent passage shaped vent opening (the crescent-shaped vent opening being defined by a housing bore and the inner sealing surfaces of the oil seal) and exerts a pressure against the oil seal which lifts or unseats the seal from engagement with the housing end wall and allows passage of oil radially outwardly into the working chamresistant to disengagement due to the pressure of oil build up in the space between the sealing edges of the oil seal opposite the crescent-shaped vent opening.

A further object of this invention is to provide an improved oil seal of the dual-sealing type in which entrapment of gas which may leak past the outer sealing edge into the space between the sealing edges is obviated.

A still further object of this invention is to provide an improved dual-sealing oil seal which is capable of maintaining a continuous uniform abutment of the sealing surfaces againstthe adjacent housing end wall by preventing lifting or disengagement of the oil seal due to fluid pressure.

'is located, relative to the direction of rotor rotation, in

the leading orfront end of each of the chambers formed between the sealing edges and positioned to extend from the front end of the chamber outwardly therefrom at an angle to an imaginary radial line in the direction of rotor rotation. This location of the vent passages minimizes the possibility of oil discharging through the vent passages because the oil, by reason of the acceleration and inertial forces, collects, relative to the direction of rotor rotation, in the trailing or rear 45' portion of the chambers. The gas vent passages are also spaced from the adjacent rib to provide a sufficiently large collecting space for oil, which space preventsthe discharge of oil in the chambers from by-passing the outer sealing edge through the gas vent passages when the gas vent passages lie coextensive with the direction of the centrifugal force acting on oil in the chambers or, when the mechanism is nonoperating and the gas vent passages extend downwardly.

It has been found desirable to construct the seal so that it has a channel or U-shape in cross-section with the legs, having at the ends thereof the sealing surfaces, inclined at approximately 60 from the plane of the housing end wall surface. It has also been found desirable that the legs be parallel and the width of the legs to be substantially the same and uniform through their effective lengths so that the sealing area, as wear of the legs occur, remains constant.

In another aspect of this invention a supplemental oil seal ring may be provided in the rotor end face radially outwardly of the oil seal ring to further minimize the possibility of oil leaking into the space between the rotor and housing.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from the following detailed description thereof when considered in connection with the accompanying drawings wherein one embodiment of the invention is illustrated by way of example, and in which:

FIG. 1 is a fragmentary view in cross-section through the rotor and housing of a rotary mechanism of the Wankel type showing a dual-sealing edge oil seal according to this invention; I

FIG. 2 is a fragmentary view in elevation of the dualsealingedge oil seal shown in FIG. 1;

FIGS. 3 and 4-are schematic drawings of a rotary mechanism of the Wankel type showing the relationship of the dual-sealing edge oil seal to the housing bore which is located coaxially of the eccentric shaft and which bore defines with the oil seal a crescent-shaped vent opening; and w FIG. 5 is a fragmentary, cross-sectional viewof alternative construction of the oil seal according to this invention.

DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION Now referring to the drawings and, more specifically, to FIGS. 1 and 2, the reference number generally designates a dual-sealing edge oil seal, according to this invention, which is shown in association with a rotor 12 of a rotary mechanism 13 of the type disclosed in the U.S. Patent to Wankel et al, US. Pat. No. 2,988,065. The oil seal 10 is mounted in a recess 14 formed in an end face 16 of rotor 12 and is resiliently biased to abut the surface 18 of the housing end wall 20 by'a suitable spring means, such as a Belleville spring 22 or an O-ring (not shown), or the like. There may also be mounted in recess 14 radially outwardly of oil seal 10a supplemental oil seal ring 24 which is biased by a suitable spring means, such as a Belleville spring 26 or the like, to abut housing end wall surface 18 and thereby assist in the prevention of the passage of oil through the interstice between housing end wall surface 18 and end face 16 of rotor 12. As is conventional in rotary mechanisms of the Wankel type, gas seals 28 are also carried in the rotor end face 16 to abut the housing end wall surface 18 and thereby function to minimize the possibility of gas passing from the working chambers 32 through the space between rotor end face 16 and end wall surface I As best shown in FIGS. 3 and 4, wherein rotary mechanism 13 is diagrammatically illustrated, rotor 12 is eccentrically mounted for rotation in the cavity formed by the housing (end wall 20 being a part of the housing) and defines with the housing a plurality of working chambers 32 which successively expand and contract in volumetric sizeas the rotor rotates. During the eccentric or orbital movement of rotor 12, the oil seal 10 slides along housing end wall 20 and is subject to varying amounts of centrifugal force during the course of a single revolution.

In rotary mechanisms of the Wankel type, such as shown in the drawings, it is the practice to journal rotor 12 on an eccentric portion of a power shaft (the axis of which is indicated at 30). A bore 36 is provided in each end wall 20 of the housing and in which bore the power shaft or crankshaft (not shown) is mounted. The bearings (not shown) between rotor 12 and the shaft eccentric (not shown) and the shaft bearings (not shown) are supplied with lubricating oil under pressure. The bore 36, in each end wall 20 (only one of which is shown in FIG. 1 is provided with an annular gutter or collecting groove (not shown) in which oil from the bearings (not shown) collects and from which it drains to'a suitable pump for recirculation. The function of oil-seal 10 is to minimize passage of oil radially outwardly into working chambers 32, via the interstices between rotor end faces 16 and the adjacent housing end wall surface 18.

As best shown in FIG. 1, each of the oil seals 10 has a channel or general U-shape in cross-section withthe distal end sealing surfaces 40 of concentrically spaced annular legs 42 and 44 abutting the adjacent end wall surface 18,-The inner legs 42 and outer leg 44, extending from a body or base portion 38, define with end wall surface 18 an annular space which is divided into a plurality of arcuate chambers 46 by circumferentially spaced, radially extending ribs or webs 48 (see FIG. 2). As best illustrated in FIGS. 3 and 4, annular legs 42 and 44 and bore 36 are so dimensioned in diameter, that as the oil seal is carried in an orbital movement relative to bore 36, a portion of the periphery of bore 36 extends or overlaps a portion of inner leg 42, but never intersects the path of travel of outer leg 44. The intersection or overlapping of bore 36 and inner leg 42 defines a crescent-shaped vent opening 50 which is represented by the hatching in FIGS. 3 and 4. The vent opening 50 functions to communicate chambers 46 with the collecting groove (not shown), via bore 36. As fully explained in the U.S. Patent to Bentele et al, U.S. Pat. No. 3,171,590,the crescentshaped vent opening 50 is always diametrically opposite to the axis 30 of rotor 12 with respect to axis 52 of the shaft (not shown) and that oil in chambers 46 will be pumped out, through the vent opening 50, and into bore 36 due to the inertial forces on the oil being directed radially inwardly- (the inertial force being a resultant force of the summation of the acceleration forces directed radially inwardly and outwardly of the vent opening 50). Thus, each time a chamber 46 comes into communication with vent opening 50, oil in chamber 46 flows outwardly therefrom into bore.36 to thereby minimize the possibility of oil build-up and a pressure developing in the chambers diametrically opposite vent opening 50 sufficient to lift or unseat sealing surfaces 40 of oil seal legs 42 and 44 from end wall surface 18 and allowing oil to pass radi- I ally outwardly toward working chambers 32. In other words,ribs or webs'48 function to angularly accelerate the oil up to the speed of the rotor so as to force the oil in chambers 46 into'communication with vent opening 50 each time a chamber registers with the vent opening so that the oil will flow out of chambers 46 and, thereby, obviate build up of oil sufficientto lift or unseat oil seal 10. i'

It has been found desirable to construct oil seal 10 so that legs 42 and 44 slant radially inwardly from base or leg portion 38 toward the axis of the oil seal and housing end wall 20 at an angle of approximately from end wall surface 18. It is also advantageous to arrange legs 42 and 44 in parallel with each other and of uniform width so that sealing surfaces 40 in their sliding movement against wall surface 18 do not vary in width. It has been found desirable to provide legs 42 and 44 with a width of less than 1 mm, preferably 0.7 mm. To insure uniform, flat or planarabutment of sealing surfaces 40 of legs 42 and 44 as the oil seal wears, the legs 42 and 44 are constructed of a uniform width or with outer leg 44 slightly narrower in width than inner leg 42.

To further minimize oil leakage past oil seal due to lifting of oil seal 10 under the build up of gas pressure in chambers 46, which gas has leaked past gas seals 28 into chambers 46, each of the chambers 46 is provided with a vent passageway means. The vent passageway means may comprise grooves or channels 56 formed in sealing surface 40 of outer leg 44 of the oil seal. Each of the channels 56 is located, relative to the direction of rotation of rotor 12 as shown by the arrow A in FIG. 2, in the leading or forward end portion of its associatedchamber 46 and extending from the chamber outwardly therefrom at an angle to an imaginary radial line in the direction of rotor rotation. Any accumulation of oil in each. of the chambers 46 does not flow through the associated channel 56 because the acceleration forces to which the oil is subjected, will force the oil against the outer peripheral wall of the chamber from where it will flow toward and accumulate in the trailing or rear portions of the chambers; thus the oil will not reach channels 56. In order to prevent the passage of oil from chambers 48, through channels 56 in positions of rotor 12 where channels 56 are coextensive with the direction of centrifugal force or extend downwardly when the rotor is stopped, each channel 56 is spaced fromthe rib 48 forming the forward wall of the associated chamber 48 to thereby provide a catch basin or sump 58 for holding oil out of communication with the associated channel. It has been found that for most operating conditions spacing the channels from the rib a distance substantially equal to the distance between legs 42 and 44 provides a sump 58 for each chamber 48 of sufficient size toreceive the oil which may normally be expected in each of the chambers 48.

In a rotary mechanism 10 of the internal combustion engine type, oil seal 10 has decreased consumption of oil to an extraordinary degree. In comparison tests of oil seal 10 with various conventional oil seals under the conditions of part-load operation at 5,000 rpm with a mean effective pressure of 1.6 kg/cm it was found, even after repeated tests, that oil consumption with oil seals 10 was many times less than with the conventional test oil seals.

In FIG. 5 is shown an alternative construction of oil seal 10 which comprises two rings 60 and 62 joined together at 64 in any suitable manner, such as by welding the oil seal.

Although two embodiments of the invenvention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the arrangement of parts without departure from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

1. In a rotary mechanism having a housing forming a cavity and a rotor supported for rotation in said cavity on an eccentric of a shaft extending through a bore in the housing side walls, an improved duaLsealing oil seal having two substantially concentrically spaced sealing surfaces extending from a body portion and forming an annulus therebetween, the dual-sealing oil seal being carried by and disposed in a recess in the rotor end face with said sealing surfaces in sliding engagement against the adjacent side wall of the housing, the improvement comprising:

a. radial wall means in the annulus of said dualsealing oil seal for dividing said annulus into a plurality of recesses to cause oil in the recesses to be rotated with the oil seal and rotor and b. gas vent passage means for each of said recesses v disposed in the dual sealing oil seal to communicate the associated recess with the portion of the cavity surrounding the dual-sealing oil seal so as to pass gas from the associated recess into said cavity.

2. The apparatus of claim 1 wherein each of said gas vent passage means is located with respect to the direction of the rotor rotation to communicate with the leading end portion of the associated recess.

3. The apparatus of claim 1 wherein said gas ven passage means is a channel formed in the outermost sealing surface.

4. The dual-sealing oil seal of claim 1 wherein said wall means is a plurality of circumferentially spaced, substantially radially extending webs.

- 5. The apparatus of claim 4 wherein each of said gas vent passage means communicates with the leading end portion with respect to the direction of rotor rotation of the associated recess ata point spaced from the web forming the leading end of the recess to thereby provide an oil collecting sump when the rotor isstationary.

6. The dual-sealing oil seal of claim 4 wherein said oil seal is generally U-shaped in cross-section and the distal end surfaces of the legs constitute said spaced sealing surfaces, the legs extending radially inwardly toward the axis of the oil seal and toward the housing side wall at an angle of approximately 60.

7. The apparatus of claim 6 wherein the legs extend parallel to each other. 7

8. The apparatus of claim 6 wherein the width of the sealing surfaces of each of said legs is less than 1 mm. 

1. In a rotary mechanism having a housing forming a cavity and a rotor supported for rotation in said cavity on an eccentric of a shaft extending through a bore in the housing side walls, an improved dual-sealing oil seal having two substantially concentrically spaced sealing surfaces extending from a body portion and forming an annulus therebetween, the dual-sealing oil seal being carried by and disposed in a recess in the rotor end face with said sealing surfaces in sliding engagement against the adjacent side wall of the housing, the improvement comprising: a. radial wall means in the annulus of said dual-sealing oil seal for dividing said annulus into a plurality of recesses to cause oil in the recesses to be rotated with the oil seal and rotor and b. gas vent passage means for each of said recesses disposed in the dual-sealing oil seal to communicate the associated recess with the portion of the cavity surrounding the dual-sealing oil seal so as to pass gas from the associated recess into said cavity.
 2. The apparatus of claim 1 wherein each of said gas vent passage means is located with respect to the direction of the rotor rotation to communicate with the leading end portion of the associated recess.
 3. The apparatus of claim 1 wherein said gas vent passage means is a channel formed in the outermost sealing surface.
 4. The dual-sealing oil seal of claim 1 wherein said wall means is a plurality of circumferentially spaced, substantially radially extending webs.
 5. The apparatus of claim 4 wherein each of said gas vent passage means communicates with the leading end portion with respect to the direction of rotor rotation of the associated recess at a point spaced from the web forming the leading end of the recess to thereby provide an oil collecting sump when the rotor is stationary.
 6. The dual-sealing oil seal of claim 4 wherein said oil seal is generally U-shaPed in cross-section and the distal end surfaces of the legs constitute said spaced sealing surfaces, the legs extending radially inwardly toward the axis of the oil seal and toward the housing side wall at an angle of approximately 60*.
 7. The apparatus of claim 6 wherein the legs extend parallel to each other.
 8. The apparatus of claim 6 wherein the width of the sealing surfaces of each of said legs is less than 1 mm. 